Women with type 1 diabetes diagnosed in childhood are more likely to have impaired bone quality in adulthood when compared with similar women diagnosed after age 20 years, further increasing their risk for fracture, according to findings from a cross-sectional study published in Bone.

“The first 20 years of growth is very important for bone health as bone mass and mineral accumulation achieves its peak during this time,” Viral Shah, MD, assistant professor of medicine and pediatrics at the Barbara Davis Center for Diabetes and the School of Medicine at the University of Colorado Anschutz Medical Campus, told Endocrine Today. “Therefore, it is possible that hyperglycemia due to type 1 diabetes during the first 20 years may have detrimental effects on bone accrual leading to compromised bone geometry and quality.”

Shah and colleagues analyzed data from 24 postmenopausal women with type 1 diabetes (mean age, 61 years; mean diabetes duration, 41.7 years) and 22 age-, sex- and BMI-matched controls without diabetes. Researchers measured areal bone mineral density at the lumbar spine, hip and distal radius via DXA and assessed bone mass, geometry and estimated bone strength at the distal and shaft of the nondominant radius and tibia using peripheral quantitative CT. Women with type 1 diabetes were stratified by early-onset (diagnosis at or before age 20 years) and late-onset (onset after age 20 years) disease.

Compared with controls without diabetes, researchers found that women with type 1 diabetes had lower trabecular volumetric BMD (least square mean, 166.1 vs. 195.9 mg/cm3; P = .02) and lower compressive bone strength (mean, 24.6 vs. 30.1 mg²/mm4; P = .04) at the distal radius, with results persisting after adjustment for age, BMI and radius length.

In analyses stratified by age of type 1 diabetes onset, researchers found that postmenopausal women with early-onset type 1 diabetes had lower total volumetric BMD (mean, 258.7 vs. 350.8 mg/cm3 ; P = .02) and lower trabecular volumetric BMD (mean, 141.4 vs. 213.6 mg/cm3 ; P = .003) vs. women with adult-onset type 1 diabetes. There was no between-group difference with respect to total area at the distal tibia. Researchers also observed a trend of larger endosteal circumference at the radial shaft among women with early-onset type 1 diabetes vs. women with adult-onset diabetes (mean, 18.2 vs. 14.3 mm; P = .09). Women with early-onset disease had larger endosteal circumference at the tibial shaft (mean, 39.1 vs. 32.1 mm; P = .005) vs. those with adult-onset disease, resulting in reduced cortical thickness (mean, 4.4 vs. 5.2 mm; P = .004). Results persisted after adjustment for age, BMI and tibia length, according to researchers.

“Our results suggest significant impairment in the bone structural quality among patients who were diagnosed with [type 1 diabetes] before the age of 20 years,” the researchers wrote. “Young-onset [type 1 diabetes] is characterized by lower trabecular [volumetric] BMD at the distal radius and cortical bone size deficit at the radial and tibial shaft. This may be due to reduced periosteal apposition and increased endosteal resorption, resulting in a cortical deficit among patients with [type 1 diabetes].” The researchers noted several study limitations, including the inclusion of only postmenopausal women, the small sample size and the limited resolution of peripheral quantitative CT, which did not allow for the evaluation of trabecular structure or cortical porosity.

“The influence of type 1 diabetes on bone accrual is unknown,” Shah said. “Longitudinal studies evaluating bone accrual in children and adolescents with type 1 diabetes compared to age-, sex-, and pubertal-matched control are much needed to understand diabetes specific factors affecting bone accrual and fracture risk in later life.” – by Regina Schaffer

For more information: Viral Shah, MD, can be reached at the Barbara Davis Center for Diabetes, Adult Clinic, School of Medicine, University of Colorado Anschutz Medical Campus, 1775 Aurora Court, Room M20-1318, Aurora, CO 80045; email: viral.shah@ucdenver.edu.

Disclosures: The Center for Women’s Health Research at the University of Colorado funded this study. Shah reports he has received grants and personal fees from Dexcom and Sanofi and grants from DiaComp, EyeNuk, the JAEB Center for Health Research and the NIH.